1. Field of the Invention
This invention relates to a new class of novel inorganic-organic hybrid polymers that are formed from linear inorganic-organic hybrid polymers of varying molecular weight. These new high temperature oxidatively stable thermosetting polymers are formed from linear polymeric materials having repeat units that contain at least one alkynyl group for cross-linking purposes and at least one bis(silyl or siloxanyl)carboranyl group and wherein the carborane content of the thermosets can be varied. These novel thermosetting polymers can be further converted into ceramics at elevated temperatures.
2. Description of the Related Art
The cross linking of acetylenic polymers has been demonstrated by Neenan et al. in Hypercross-Linked Organic Solids: Preparation from Poly(aromatic diacetylenes) and Preliminary Measurements of Their Young's Modulus, Hardness, and Thermal Stability published in 21 Macromolecules 3525-28 (1988), incorporated herein by reference. Other similar cross linking reactions are demonstrated by Callstrom et al. in Poly[ethynlyene(3-n-butyl--2,5-thiophenediyl)-ethynylene]: A Soluble Polymer Containing Diacetylene Units and Its Conversion to a Highly Cross-Linked Organic Solid published in 21 Macromolocules 3528-30 (1988), incorporated herein by reference. The recent literature reflects continuing major research efforts to advance fundamental knowledge in high temperature material design. See K. J. Wynne and R. W. Rice, Ceramics Via Polymer Pyrolysis 14 Ann. Rev. Mat. Sci. 297 (1984) incorporated herein by reference in its entirety and for all purposes. In the search for high temperature oxidatively stable materials considerable attention has been given to polymers containing boron within the polymer. It has been known that the addition of a carborane within a siloxane polymer significantly increases the thermal stability of such siloxane polymers.
The thermal properties of various siloxane polymers are given by Petar Dvornic et al. in High Temperature Siloxane Elastomers published by Huthig & Wepf Verlag Basel, New York (1990) on pp. 277 in FIG. 5.7 and on pp.282 in FIG. 5.12 and by Edward N. Peters in Poly(dodecacarborane-siloxanes) published in J. Macromol Sci.-Rev. Macromol. Chem., C17(2) on pp. 190-199 in FIGS. 3,4,5,6,7,10 and 12, each reference being incorporated herein by reference in its entirety and for all purposes. See also Maghsoodi et al. in Synthesis and Study of Silylene-Diacetylene Polymers published in 23 Macromolecules pp. 4486 (1990), incorporated herein by reference in its entirety and for all purposes.
Many of the carborane polymers manufactured are cited in various U.S. patents. See, for instance, the following U.S. Pat. Nos.: 5,348,917; 5,292,779; 5,272,237; 4,946,919; 4,269,757; 4,235,987; 4,208,492; 4,145,504; 3,661,847; 3,542,730; 3,457,222; and 3,234,288, each patent being incorporated herein by reference in its entirety and for all purposes.
There is a need for oxidatively stable ceramic materials suitable for making rigid components therefrom (e.g. by combining with fiberglass or carbon matrix or other matrix fibers, respectively), such as engine parts, turbine blades and matrices. These components must withstand high temperatures and be oxidatively stable and have sufficient strength to withstand the stress put on such components.
There is a need for carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content of the ceramics can be varied by varying the carborane content of the precursor thermosetting polymers. Weight percentage loss of the ceramic materials is limited to 50% or less from the original total weight or where the weight percentage loss is limited to 40% or less after formation of the precursor thermoset when heated in excess of 400 to 700.degree. C. in an oxidative environment.
There is a need for carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content of the ceramics can be varied by varying the carborane content of the precursor thermosetting polymers. Weight percentage loss of the ceramic materials is limited to 30% or less from the original total weight or where the weight percentage loss is limited to 15% or less after formation of the precursor thermoset when heated in excess of 400 to 700.degree. C. in an oxidative environment.
There is a need for carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content of the ceramics can be varied by varying the carborane content of the precursor thermosetting polymers. Weight percentage loss of the ceramic materials is limited to 20% or less from the original total weight or where the weight percentage loss is limited to 10% or less after formation of the precursor thermoset when heated in excess of 400 to 700.degree. C. in an oxidative environment.
In addition, there is a need for carborane-silane and/or carborane-siloxane ceramic materials that behave more as rigid materials and less as elastomeric materials and wherein the carborane content of the ceramics can be varied.
There is a further need to provide carborane-silane and/or carborane-siloxane ceramic materials wherein the carborane content within the ceramics can be varied to provide maximum thermal stability and minimum cost.
In addition, a majority of the carborane-siloxane and/or carborane-silane polymers made by others show elastomeric properties rather than properties of more rigid products like ceramics. Thus, in addition to thermal stability, there is also a need for materials that behave more as ceramics, upon further polymerization, and less like elastomeric polymers.